ESTOP_LATCH

NAME

SYNOPSIS

DESCRIPTION

This component
can be used as a part of a simple software ESTOP chain.

It has two
states: "OK" and "Faulted".

The initial
state is "Faulted". When faulted, the
out-ok output is false, the fault-out output
is true, and the watchdog output is unchanging.

The state
changes from "Faulted" to "OK" when
all these conditions are true:

•

fault-in is false

•

ok-in is true

•

reset changes from false to true

When
"OK", the out-ok output is true, the
fault-out output is false, and the watchdog
output is toggling.

The state
changes from "OK" to "Faulted" when
any of the following are true:

•

fault-in is true

•

ok-in is false

To facilitate
using only a single fault source, ok-in and
fault-en are both set to the non-fault-causing value
when no signal is connected. For estop-latch to ever be able
to signal a fault, at least one of these inputs must be
connected.

Typically, an
external fault or estop input is connected to
fault-in, iocontrol.0.user-request-enable is
connected to reset, and ok-out is connected to
iocontrol.0.emc-enable-in.

In more
complex systems, it may be more appropriate to use
classicladder to manage the software portion of the estop
chain.